Conventionally, as a technique used for a method for adjusting white balance of a color image, which is a correction method suitable for specific chromatic colors, human memory colors and the like, a technique has been known that whether or not color shown by each pixel is included in a range of predetermined color is judged, and when the color shown by each pixel is included in the range of the predetermined color, the deviation amount of the color shown by the pixel and the predetermined color is able to be obtained (for example, see Patent Literature 1).
In addition, various types of formats of input image data are known. As representative methods, YUV expressed by luminance (Y), color difference (U) which is difference between blue components and luminance, and color difference (V) which is difference between red components and luminance, RGB expressed by a value of red color (R), a value of green color (G), and a value of blue color (B), and the like are known.
In particular, several formats are defined for YUV. For example, various formats are known, including YUV444 (24 bits/1 pixel) in which each of YUV is comprised of 1 sample in each pixel, YUV422 (16 bits/1 pixel) in which Y is comprised of 2 samples and each of UV is comprised of 1 sample in two pixels, YUV420 (12 bits/1 pixel) in which Y is comprised of 4 samples and each of UV is comprised of 1 sample in 4 pixels of 2×2, YUV411, YUV9 and the like.
To show with drawings, YUV444, YUV422 and YUV420 are schematically shown in FIG. 32(a), FIG. 32(b) and FIG. 32(c), respectively.
That is, in YUV422 of FIG. 32(b), based on a pixel shown with a bold line (this pixel serving as a basis is referred to as a “reference pixel”), other pixel shares the same pixel value as the reference pixel as to color difference U and color difference V (other pixel which share in a part of the pixel value with the reference pixel is referred to as a “shared pixel”). Moreover, YUV420 of FIG. 32(c) is comprised of the reference pixel shown with a bold line and other three pixels as shared pixels.